Can be mounted just about anywhere. My horses have indoor stalls with an outdoor paddock attached. The salt brick holders are mounted on the wall inside the stalls and the horses don't pull the salt out - they just stand and lick the salt when they want it.

These salt block holders are so much more durable than the plastic coated ones and less dangerous to the horses, as no coatingto peel off. These are sturdy, offer a larger surface for the horses to get at, lick, but most importantly the blocks hold in so much better. Of course the horses can eventually pull the block as they get smaller, but love these holders 100%.